The present invention relates to spraying systems, particularly systems for spraying coating materials under relatively high material pressure conditions. The invention is particularly adapted to portable spraying systems wherein a gasoline engine or equivalent drives a hydraulic pump, and the pump delivers the spraying materials to a spray gun connected to it by a section of elongated hose.
Advances in hydraulic pump designs have enabled spraying systems to be developed for delivering coating materials under relatively high hydraulic pressures. It is not uncommon for such systems to be pressurized coating materials to hydraulic pressures in the range of 1,000-4,000 pounds per square inch (psi), for under such highly pressurized conditions it is usually possible to obtain a higher quality spray finish. On the other hand, coating materials themselves have been changed to encompass a wide range of viscosities, wherein high viscosity coating materials require extremely high hydraulic pressures for atomization and delivery to a coating surface. The present invention is particularly adapted for spraying heavily viscous, textured materials, but the principles of the invention are applicable to a wide range of coating materials. Such materials are usually sprayed under hydraulic pressure conditions which are less than 1,000 psi, and greater than approximately 100 psi. Portable systems for spraying materials of this type may be conveniently driven by relatively small gasoline engines which are mechanically linked to hydraulic pumps, and wherein the pumps are linked to a spray gun by hoses. In many cases such materials may be sprayed using air spray techniques, wherein pressurized air is also delivered to the spray gun to either atomize the coating materials as they are emitted from the spray gun, or assist in the atomization of the coating materials, which are atomized both under the influence of hydraulic pressure and air pressure. Systems of this type require a power source for developing the hydraulic pressure required, and also a source of compressed air for providing a supply of pressurized air, but the respective pressure ranges are much more moderate than pressures required in systems where hydraulic pressure alone is utilized.
Any spraying system operating under even moderate pressure conditions requires certain safety features for protection of the system operator. In particular, the operator must be protected from inadvertent exposure and contact with the materials emitted from the spray gun, particularly in close proximity to the spray tip. The system should provide safeguards to minimize the operator's potential for injury from highly pressurized equipment and materials.